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Lithium (Li) and its isotopes are potential tracers of silicate weathering in river basins. However, the relationship between the Li isotopic composition (δ7Li) in rivers and silicate weathering intensity remains unclear. This study analyzed the Li concentration and isotopic composition in river waters from the Niyang River, southern Tibetan Plateau. The results show that these samples have significantly variable Li concentrations (0.31-7.4 μg/L) and δ7Li values (+7.0-+20.7%o, n=28), and high δ7Li values are found in several tributaries. Calculations indicate that dissolved Li in river water is predominantly derived from silicate weathering and geothermal water. With the exception of certain tributaries, geothermal water contributes 68% to 85% of the dissolved Li. Geothermal waters have low δ7Li values (−0.9-+2.9%o) in the Tibetan Plateau. Differences in the proportional contribution of dissolved Li in river samples from silicate weathering and geothermal water may be the main reason for the spatiotemporal variation in riverine δ7Li values. The samples have higher δ7Li values when the dissolved Li in the water samples is mainly derived from silicate weathering contributions, and lower values when the contribution from geothermal waters is high. Furthermore, the interaction of dissolved Li from geothermal water with secondary minerals results in Li isotopic fractionation, which may contribute to variations in river water δ7Li. It is accepted that the lower weathering intensity in orogenic (or mountainous) belts compared to floodplains is the main controlling factor for lower δ7Li values in the rivers. This study indicates that geothermal water input may cover the Li isotope signal of silicate weathering in river water, which in turn, affects the accurate understanding of the relationship between riverine δ7Li values and the silicate weathering intensity. Therefore, whether the lower δ7Li values of river waters in hydrothermal-rich orogenic belts are mainly controlled by the regional weathering intensity or the input of hot springs (or both) requires in-depth study, and this is the key to accurately establishing the relationship between the Li isotopic composition and silicate weathering intensity in the river basin. [ABSTRACT FROM AUTHOR]

The Weining Beishan area of Ningxia Hui Autonomous Region is located at on the western edge of the Helanshan tectonic belt, which is a tectonic joint among Alxa Block, Ordos Block, and North Qilian orogenic belt. However, the tectonic evolution of this area remains unclear due to the lack of magmatic information. This paper conducted researches on geochronology, geochemistry, and Sr-Nd-Hf isotopes of the diorite porphyrites exposed in the Weining Beishan area. The zircon U-Pb dating yields two ages of 145.0 ± 1.1 and 146.2 ± 1.5 Ma, and the whole-rock geochemical data indicate that the diorite porphyrites are metaluminous to weakly peraluminous and high-K calc-alkaline series. The characteristics of highly initial 87Sr/86Sr ratios (0.708 16 to 0.710 47), negative εNd(t) (−8.9 to −8.4), and negative εHf(t) (−13.8 to −21.2) indicate that the diorite porphyrites originated from partial melting of the middle-lower ancient crust related to the North China Craton. Combined with the regional geology, we suggested that partial melting was triggered by a tectonic activity of deep faults cutting through the crust under the regional stress transformation from compressing to extension during the Late Jurassic–Early Cretaceous, which is probably related to the westward subduction of the Paleo-Pacific Plate. [ABSTRACT FROM AUTHOR]

The detrital zircon records significant information in the 'source‐sink' system. With the application of in situ laser ablation technology, a large number of high‐quality detrital zircon data have been published since 2000. In this study, a total of 41,342 detrital zircon U–Pb ages and 6,129 Hf isotopes were compiled from the published literatures of the Middle East (Iranian and Arabian plates). Through data filtering and recalculation, valid data were employed for further analysis. The detrital zircons from the Middle East show a Cambrian–Precambrian age population of 500–1,000 Ma, with a major age peak of ~620 Ma and dispersed εHf(t) values of −35 to +20. The Alborz Mountains and central Iran terrane show a Permo–Triassic age range of 200–300 Ma. The Mesozoic–Cenozoic detrital zircons are mostly occurred in the Zagros orogenic belt and Makran accretionary complex, with three obvious age ranges of 145–180 Ma, 80–110 Ma and 15–65 Ma. The Mesozoic zircons yield positive εHf(t) values, while Cenozoic zircons have varied εHf(t) values. This database allows for the further exploration of the provenance analysis and application in constraining the timing of the major tectonic events in the Middle East, and may also help to explore the affinities of plates, thus guiding future palaeogeographic research efforts. [ABSTRACT FROM AUTHOR]

The Hongshishan chromitite deposits are situated to the north of the Beishan orogenic collage, in the southern part of the Central Asian Orogenic Belt. This study describes the mineral chemistry, Re‐Os isotopes and platinum‐group elements geochemistry of the Hongshishan chromitites for the purpose of constraining the origin, evolution and composition of their parental melts. The restricted ranges of Al2O3, Cr2O3 and Cr#‐Mg# variation of chromite‐cores and chromites fall within the field of the mid‐ocean ridge and ophiolitic podiform chromite settings. The (187Os/188Os)i ratios of the chromitites are in the range of 0.12449–0.12745 (average 0.12637) and the γOs are from –1.92 to –0.06 (average –0.83). In the Re‐Os isotope diagrams, all the samples fall in the field of chromitites and show a residual peridotitic trend. The range of Os isotopic compositions and γOs values indicate that they overlap the depleted MORB mantle (DMM) as well as being close to global Os isotopic data and γOs of ophiolite chromitites. The characteristics of the PGE contents can be roughly subdivided into two groups: podiform chromitites and Ural‐Alaskan type complexes. For the ferritchromite cores, the calculated Al2O3 concentrations of the parental melt are higher (average 16.65 wt%) in high‐Cr than high‐Al chromitite (average 16.17 wt%) and for the chromite, the calculated Al2O3 concentrations are even higher (average 16.48 wt%) in the high‐Cr than the high‐Al examples (average 15.38 wt%). In the (TiO2)melt vs. TiO2 diagrams, most high‐Al melts fall in the MORB, while the high‐Cr melts fall in the ARC field. The calculated FeO/MgO ratios for the parental melt show the closest resemblance to a MORB magma composition. The inferred parental melt composition for studied chromitites falls in the field of mid‐ocean ridge basalt (MORB) magmas and far away from boninite. The calculated degrees of partial melting producing the chromitites are 16%–22% (average 19%), which is around the range of those of the MORB magmas. The chromitites are suggested to have been formed in a MORB setting. The chromites and ferritchromite cores are mostly scattered along the MORB and SSZ harzburgite–dunite fields. Ferritchromite rims and ferritchromites with high YFes formed as a result of alteration during serpentinization.. [ABSTRACT FROM AUTHOR]

The Nianzi granite unit, which includes the Nianzi, Xiaolianghou and Xiawopu granitic intrusions, is a significant component of the northern part of the North China Craton (NCC) and is situated in the Yanshan fold and thrust belt (YFTB). However, there is still debate regarding the tectonic evolutionary history of the YFTB during the late Permian to Triassic period, specifically regarding the timing of subduction and collision between the NCC and the Paleo‐Asian Ocean. The Nianzi granite unit exhibits unique petrological, geochronological and geochemical signatures that shed light on the tectonic evolutionary history of the YFTB. This study presents detailed petrology, whole‐rock geochemistry, together with Sr‐Nd isotopic, zircon U‐Pb dating and Lu‐Hf isotopic data of the granites within the Nianzi granite unit. Our findings demonstrate that the granites primarily consist of subhedral K‐feldspar, plagioclase, quartz, minor biotite and hornblende, with accessory titanite, apatite, magnetite and zircon. Zircon U‐Pb dating indicates that the Xiaolianghou granite was emplaced at 247.5 ± 0.62 Ma. Additionally, the adakitic characteristics of the Nianzi, Xiawopu and Xiaolianghou granitic intrusions, such as high Sr and Ba contents and high ratios of Sr/Y and (La/Yb)N, combined with negative Sr‐Nd and Lu‐Hf isotopes (87Sr/86Sr)i = 0.705681–0.7057433, εNd(t) = –21.98 to –20.97, zircon εHf(t) = –20.26 to –9.92), as well as the I‐type granite features of high SiO2, Na2O and K2O/Na2O ratios, enriched Rb, K, Sr and Ba, along with depleted Th, U, Nb, Ta, P and Ti, suggest that the Nianzi granitic unit was mainly derived from the partial melting of a thickened lower crust containing hydrous, calc‐alkaline to high‐K calc‐alkaline, mafic to intermediate metamorphic rocks. In light of these parameters, we further integrate our data with previous studies and conclude that the Nianzi granitic unit was generated in a post‐collisional extensional environment during the Early Triassic. [ABSTRACT FROM AUTHOR]

Magmatic activity in the Sakarya Zone, an important segment of the Alpine orogenic belt, continues intermittently from the middle Carboniferous to Miocene. In this study, we provide geochronological and geochemical data from the Dağdibi Pluton in the eastern Sakarya Zone to present some inferences on the source region and petrogenesis of the middle Eocene magmatism. U–Pb zircon geochronology from two granodiorite samples gives middle Eocene ages of 44.75 ± 0.92 and 45.01 ± 0.59 Ma. The pluton is mainly composed of K-feldspar, plagioclase, quartz, Mg-hornblende/actinolite, Fe–Ti oxides and small amounts of biotite, and secondary chlorite and epidote. Parental magma of the intrusive rocks has a high-K calc-alkaline affinity with metaluminous character. The oxygen fugacity values vary between −18 and −17. The rocks show slightly radiogenic 87Sr/86Sr(i) (0.704845–0.705726) ratios and ϵNdi values between −0.96 and +0.52. Pb–Pb isotope ratios are typical for those of the lower continental crust. ϵHf(i) values of the zircons range from 0.14 to 10.26. The geochemical and isotopic features of the pluton point to a parental magma derived from a depleted mantle that was metasomatized by fluids during previous subduction events. The volumetric abundances of the rock types are decreased as the silica content increase, implying that the fractional crystallization is the most important process during the formation of the present compositional range of the pluton. Amphibole, plagioclase and Fe–Ti oxides are the fractionated phases while K-feldspar is largely accumulated. In the light of the data presented above, slab breakoff is regarded as the geodynamic process responsible for the formation of the Dağdibi Pluton in the middle Eocene. [ABSTRACT FROM AUTHOR]

The subcontinental lithospheric mantle (SCLM) is now suggested by many workers to play a role in the formation of orogenic gold deposits in active continental margins, given that the gold and volatiles may be introduced into the SCLM during plate subduction. The giant Cretaceous Jiaodong gold province within the North China block occurs in a convergent margin setting where there is no terrane accretion, thus eliminating from consideration the commonly accepted metal and fluid source reservoir for orogenic gold--the metamorphosed upper crust of an active orogenic belt. Thus, the auriferous fluids were released below the high-grade Archean cratonic rocks from either enriched SCLM or directly from the subducted oceanic slab. Mercury (Hg) isotopes allow fingerprinting of isotopically distinct reservoirs, discriminating between the two possibilities. We present Hg isotope data for a set of pyrite grains, native gold, and lamprophyres from six main gold districts in the Jiaodong gold province. These samples dominantly yielded near-zero Δ199Hg (0‰ ± 0.1‰), within uncertainty of the mantle Δ199Hg value. The results provide novel evidence that the SCLM predominantly controlled the Hg budget of the Jiaodong gold deposits, implying that the SCLM acted as a buffer for the crustal mass-independent fractionation Hg signatures and a storage reservoir for gold and volatiles. Consequently, during slab subduction, gold and volatiles were recycled and stored within the SCLM and were later released from the mantle during uplift and relaxation of compressional tectonics. [ABSTRACT FROM AUTHOR]

The late Palaeozoic continental-arc magmatic rocks in the Gongzhuling area are located in the Liaoyuan Accretionary Belt. Here we present new zircon U–Pb ages, whole-rock major- and trace-element compositions, Li and zircon Hf isotopic compositions and oxygen fugacity of these rocks with an aim to constrain the lithium isotopic composition of the source region and origin of the magmas. These rocks were formed during 269–258 Ma in middle–late Permian time. The dioritic rocks were formed through mixing processes, with the mafic melts originating from a metasomatized mantle wedge and the felsic melts from the lower crust of a Neoproterozoic arc. The mantle wedge has been metasomatized by Li-rich fluids derived from subducted oceanic crust, as indicated by the δ7Li values of +0.4 ‰ to +3.5 ‰ and positive ϵHf(t) values (+0.7 to +13.1). Redox-sensitive Ce in the zircons indicates the f O2 of the magmas to be low to intermediate (FMQ−2.2 to FMQ+2.6; FMQ is the fayalite–magnetite–quartz redox buffer), precluding large-scale porphyry Cu–Mo mineralization. The middle–late Permian magmatic rocks represent the terminal magmatic record of the subduction of the Palaeo-Asian oceanic crust, meaning that the final closure of the Palaeo-Asian Ocean in the eastern Central Asian Orogenic Belt occurred at the end of the Permian Period. Recent identification of Mesoproterozoic (c. 1400 Ma) granites suggests some Palaeoproterozoic crustal fragments still exist in the Liaoyuan Accretionary Belt, but only in a small amount; therefore, it is concluded that the crustal growth of the Liaoyuan Accretionary Belt occurred mainly during the Neoproterozoic period. [ABSTRACT FROM AUTHOR]

Oceanic arcs are crucial sites for producing new continental crust. However, how the continental crust has acquired its bulk "andesitic to dacitic" compositions is not well-understood. To address this issue, we carry out an integrated study for granitoids from the East Junggar oceanic arc, Central Asian Orogenic Belt. All the granitoid samples with ages of 332–280 Ma have high SiO2 but low MgO contents, indicating a dominant crustal source. Based on zircon O isotopes, these granitoids can be divided into three groups: Group I (5.0 ± 0.46‰, 2SD), Group II (8.6 ± 0.47–9.4 ± 0.52‰, 2SD) and Group III (6.8 ± 0.36–7.4 ± 0.48‰, 2SD) with mantle-like, elevated and intermediate zircon δ18O ratios, respectively. The formation of Group I granitoids can be ascribed to partial melting of juvenile mafic crust, while Group II and III granitoids were likely derived from a mixed source of juvenile mafic crust and supracrustal rocks in variable proportions. Combined with their depleted mantle-like zircon εHf(t) values (+ 11.6 to + 13.5), it is inferred that these supracrustal rocks were mainly isotopically unevolved, immature volcanogenic sediments. The zircon Hf–O isotope array is compatible with mixing between juvenile mafic crust and supracrustal volcanics (40–70% for Group II and 20–40% for Group III) in their magma sources. The incorporation of supracrustal rocks into such high-δ18O granitoids was likely associated with fore-/intra-arc basin closure triggered by arc–arc collision. Our results thus highlight the role of supracrustal recycling induced by collisional events in driving the compositional differentiation of oceanic arc crust from basaltic to felsic. [ABSTRACT FROM AUTHOR]

The Late Cretaceous magmatic history of the Eastern Pontides Orogenic Belt (NE Turkey) was generally characterized by common I-type and lesser A-type plutons in varying size and composition. Of these, A-type plutons from the Şebinkarahisar (Giresun) area yield SHRIMP zircon U-Pb age of 77.36 ± 0.96 Ma. The rocks of these plutons display a wide range of SiO2 contents (53.63 to 70.96 wt.%) and Mg-numbers (6.2–32.19) with A-type affinities characterized by enrichment in K2O and Na2O, Ga, Zr, and strong negative Eu anomalies. They also show arc-type petrochemical features including enrichment of large-ion lithophile elements (e.g. Cs, K, Rb) and light rare earth elements (LaN/LuN = 6.27–15.61), but depletion in high strength field elements (e.g. Nb, Ta, Ti, and P). The (87Sr/86Sr)i ratios and ɛNd(i) values of the studied rocks are in the range of 0.705129 to 0.0705347 and −3.64 to −3.12, respectively, while bulk rock ɛHf(i) values are between 1.86 and 4.36. They are characterized by positive zircon ɛHf(i) (1.74 to 10.88) plotting between the chondrite and depleted mantle evolutionary line values. Our data combined with the previous studies suggest that the magmas, that formed the Late Cretaceous plutons, were generated in an extensional tectonic environment due to slap roll-back and trench ward migration of the subduction zone to the south. The generation of hybrid magmas forming the studied plutons is in response to the melts derived from a metasomatized lithospheric mantle source, a relatively deeper mantle source, and the juvenile crust along with the heat transfer and decompression. Multi-sourced magmas rise through the continental crust and reach the final composition by predominantly fractional crystallization processes. [ABSTRACT FROM AUTHOR]

Nine Paleozoic sedimentary formations from western Tasmania and two from the Lachlan Orogen—one in northeast Tasmania and one in Waratah Bay in Victoria—contain detrital zircons that fall into major U–Pb age clusters at 2.0–1.4, 1.25–0.95 and 0.62–0.49 Ga. The zircon Th/U ratios and rare earth element (REE) patterns suggest a magmatic origin for detrital zircons in all these rock sequences. The REE geochemical signatures on bivariate discrimination diagrams indicate that most of the zircons originated in continental orogenic settings. The oldest group of zircons have a southwest Laurentian signature previously recognised from Proterozoic metasedimentary rocks in Tasmania. The 1.25–0.5 Ga zircons from all the samples have very similar εHfi values. They are not statistically different from those of typical Lachlan Orogen sandstones and resemble those in Rodinia and early Gondwana orogenic belts. The εHfi values of the Cambrian zircons within the Pioneer Sandstone are similar to the Mount Read Volcanics but cannot be distinguished on εHfi values from other sources in East Gondwana. The detrital zircon provenance of the Bear Gully Chert Bed at the base of the Digger Island Marlstone at Waratah Bay includes the west Tasmanian Proterozoic, the East Gondwana margin and the Macquarie Arc. This mixed provenance provides evidence for the late Cambrian docking of VanDieland with East Gondwana. New zircon Hf isotope data are reported for early Paleozoic sedimentary rocks in Tasmania and Waratah Bay, southern Victoria. The western Tasmania basement was the dominant source for Tasmanian sandstones and a minor source for the Lachlan Orogen sandstones on the northeast margin of VanDieland. The mixed provenance of the Bear Gully Chert supports a late Cambrian accretion of VanDieland to the East Gondwana margin. The youngest zircons in the Bear Gully Chert at Waratah Bay were potentially sourced from the Macquarie Arc. [ABSTRACT FROM AUTHOR]

The role of metasomatized mantle in the genesis of magmatic Ni–Cu sulfide deposits in orogenic belts remains vigorously debated. The greatest challenge in clarifying uncertainties is how to track the behavior of metals during metasomatic processes in the mantle. Copper isotopes can shed new light on this enigmatic topic as the transfer of Cu during metasomatic processes can significantly fractionate Cu isotopes. In this regard, we have characterized the Cu isotope and trace-element compositions of fertile and barren mafic–ultramafic intrusions, and coeval basalts in the Eastern Tianshan, Central Asian Orogenic Belt (CAOB). Fertile mafic–ultramafic intrusions are characterized by elevated and highly variable Ba/Nb (40–756, average of 172) and Ba/La (16–219, average of 48) ratios, and exhibit δ65Cu values (−0.97 ‰ to +0.57 ‰) that vary over 1.54 ‰. In contrast, barren intrusions and coeval Permian basalts are characterized by relatively low and invariable Ba/Nb (2–95, average of 29) and Ba/La (0.9–26, average of 8) ratios, and have δ65Cu values that are comparatively less variable (−0.06 ‰ to +0.49 ‰ for δ65Cu) and more similar to bulk silicate Earth (BSE, δ65Cu = 0.06 ± 0.20 ‰). The difference in Cu isotope compositions of fertile and barren intrusions, alongside the variability in Ba enrichment, suggests that a high degree of mantle metasomatism promotes the fertilization of primary magmas in metals and, thus, represents one of the first stages in the development of magmatic Ni–Cu sulfide deposits in convergent margins. [ABSTRACT FROM AUTHOR]

This study adopts a new approach describing palaeohydrology and palaeoclimates based on the interpretation of stable oxygen isotopes (δ18 O p) recorded in fossil crocodilian teeth. They represent an archive of prime interest for tracking freshwater palaeoenvironmental change, applicable to many palaeontological localities in the world: crocodilian teeth are abundant in continental basins and have been widely distributed since their diversification during the Mesozoic; the enamel phosphate is resistant to diagenesis and retains its original isotopic composition over geological timescales; and their δ18 O p mainly relies on that of the crocodilian's home waterbody (δ18 O w), which in turn reflects waterbody types, regional climate, and evaporation conditions. This study presents the first application of this theoretical interpretative model to the Shungura Formation (Lower Omo Valley, Ethiopia), a key witness of the important environmental change in eastern Africa during the Plio-Pleistocene that impacted the evolution of regional faunas, including humans. In this complex and variable environmental context, the δ18 O p of coexisting crocodilians allows for the fingerprinting of the diversity of aquatic environments they had access to at a local scale. This study sheds light on two important results: the δ18 O p of crocodilian teeth (1) indicates stable aquatic environments in the northern Turkana Depression from 2.97 to ca. 2.57 Ma but a decline in local waterbodies diversity after 2.32 Ma, suggesting increasing aridity, and (2) shows, like previous geochemical studies on palaeosols and bivalves in the area, a significant increase in δ18 O w from 2.97 to ca. 1.14 Ma, likely due to the shifting air stream convergence zones between the West African and Indian Summer Monsoons and/or reduced rainfall over the Ethiopian Highlands. [ABSTRACT FROM AUTHOR]

There is a magmatic lull period in the East Kunlun orogen (EKO) during the Jurassic to the Cretaceous. However, due to the lack of records of magmatic activity restricts our understanding of the late Mesozoic magmatic-tectonic evolution of the EKO. Herein, an integrated study of geochronology, whole-rock geochemistry and Sr-Nd isotopes were conducted for the Cretaceous mafic dykes in the EKO, Northern Tibet Plateau, to reveal their petrogenesis and geodynamic implications. LA-ICP-MS Zircon U-Pb dating reveals that the studied mafic dykes comprising diabase and diabase porphyry emplaced at ca. 80.9 ± 0.8 Ma. The Cretaceous mafic dykes have low contents of SiO2 (46.36 wt.%~47.40 wt.%) but high contents of MgO (6.79 wt.%~7.38 wt.%), TiO2 (1.91 wt.%~2.13 wt.%), Nb (12.4~18.3 ppm) and Nb/U ratio (31~39), resembling Nb-enriched mafic dykes. They exhibit chondrite-normalized rare earth element (REE) and primitive mantle-normalized trace element patterns, remarkably similar but not identical to the oceanic island basalts (OIB). The moderate REE fractionation ((La/Yb)N = 3.55~5.37), weak negative Eu anomalies (δEu = 0.87~0.97) and relative enrichment of Rb, Ba, K, as well as high contents of Cr and Ni and slightly depleted Sr-Nd isotopes (εNd(t) = −0.18~1.33), suggest that the studied dykes originate from a partial melting of spinel lherzolite and a little of garnet which was previously modified by subducted sediments. Combined with other evidence, we propose that the studied Cretaceous Nb-enriched mafic dykes in the Northern Tibet Plateau were formed in the intraplate setting, which may be a partial melting of the enriched mantle in the lower lithosphere caused by the activity of the East Kunlun strike-slip fault. [ABSTRACT FROM AUTHOR]

Weakly disseminated sulphide mineralization is present in the outcrops of several mafic–ultramafic intrusions in the Beishan region of the Central Asian Orogenic Belt in western China, but the potential of these intrusions to host economic sulphide ores at depths is not known. A better understanding of the genetic control on the mineralization may help to answer this important question. With this in mind, we have selected two of them that were emplaced during the Devonian, a period when subduction-related mafic magmatism undoubtedly occurred in the region, for a geochemical study. They are the Miaomiaojing and Guaishishan mafic–ultramafic intrusions. Our new zircon U-Pb dating indicates that they were emplaced at 377.5 ± 5.3 and 358.6 ± 3.9 Ma, respectively. Lherzolite, olivine websterite, troctolite and gabbro are the main rock types for both intrusions. Disseminated sulphide mineralization is concentrated in the ultramafic units of both intrusions. The whole-rock samples are characterized by light REE enrichments, pronounced negative Nb-Ta anomalies, and variable εNd(t) values from −3.54 to +2.17. Zircons from the intrusions have elevated δ18O values (average value: 7.48 ± 0.09 ‰) compared to that of the mantle. The trace element and isotope data support the interpretation that the parental magmas for the Devonian mafic–ultramafic intrusions are contaminated arc mafic magmas. Petrological modelling reveals that fractional crystallization together with crustal assimilation may have played an important role in triggering the sulphide saturation in the magmas. The Ni tenors (in recalculated 100% sulphide) for the sulphide-mineralized samples from both intrusions are similar and up to 6.7 wt% Ni and 2.8 wt% Cu, comparable to the metal tenor of most economic Ni-Cu deposits in the CAOB, implying that samples containing higher amounts of sulphides would become Ni-Cu ores. The olivine Fo and Ni contents from sulphide-bearing ultramafic rocks show a negative correlation, consistent with sub-solid Fe-Ni exchange between olivine and sulphide melt. Together with the similar mineralization characteristics between these sulphide-bearing intrusions and the coeval Heishan Ni-Cu deposit, we suggest that these intrusions have the potential to host Ni-Cu sulphide ores at depths, which could be further tested by geophysical survey followed by drilling. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sphalerite is an important host for In and Cd, and tennantite is the main host for Au, Ag, As, Cd, Sb, Zn, Bi, and Se in base metal sulfides system. The concentration fluctuation of Bi and Se may be caused by galena. • The Re–Os weighted average age of pyrite indicates that the No. I mineralized belt formed at 389.1 ± 9.9 Ma (MSWD = 0.15). The sulfur of deposit mainly comes from magmatic sulfur, followed by seawater sulfate. • The geothermometer of sulfur isotope shows sulfide mainly formed at 113–362 °C (avg. 214 °C), and sphalerite formed at 133–194 °C (avg. 175 °C) based on GGIMFis geothermometer. The Ashele Cu–Zn deposit is the largest volcanogenic massive sulfide (VMS) type deposit in the Xinjiang Central Asian Orogenic Belt (XCAOB). This deposit is located in the Devonian volcanic–sedimentary basin on the South Altay, Xinjiang. The Nos. I and II mineralized belts are the largest in the ore district consist of two parts: concordant massive sulfide lenses and discordant vein-type sulfide mineralization. This study mainly focuses on the mineralization during the submarine exhalative–sedimentary period. In situ trace element analysis showed that sphalerite is an important host for In and Cd, and tennantite is the main host for Au, Ag, As, Cd, Sb, Zn, Bi, and Se in base metal sulfides system. The concentration fluctuation of Bi and Se may be caused by galena. Pyrite and chalcopyrite are not enriched with specific elements, except for occasional inclusions of other minerals. Seven stratified pyrite samples display a Re–Os weighted average age of 389.1 ± 9.9 Ma (MSWD = 0.15). This data can represent the formation time of the No. I mineralized belt. The geothermometer of sulfur isotope shows sulfide mainly formed at 113 to 362 °C (avg. 214 °C), and sphalerite formed at 133 to 194 °C (avg. 175 °C) based on GGIMFis geothermometer. The δ34S values are between −1.84 to 5.51 ‰, suggestting sulfur mainly comes from magmatic sulfur, followed by seawater sulfate. [ABSTRACT FROM AUTHOR]

Many high silica granites (>70 wt% SiO 2) are closely linked to ore deposits. There has been an ongoing debate about whether they are formed through extensive fractional crystallization or partial melting, as traditional major-trace element and radiogenic isotopes make it challenging to distinguish among these mechanisms. Recent studies suggest that zinc isotopes have the potential to trace crustal differentiation and monitor fluid evolution during the late stage of magma evolution. In this study, we investigated the Lenglongling leucogranites in the North Qilian Orogenic belt, characterized by high SiO 2 contents ranging from 72 % to 78 wt%, extremely low Zr/Hf ratios (15.8–21), low Nb/Ta ratios (3.8–9.3), and strongly negative Eu/Eu* anomalies (0.04–0.32). The invariant and basalt-like zinc isotopic compositions of the Lenglongling high silica leucogranites (0.27 ‰ ±0.03 ‰ to 0.38 ‰ ± 0.03 ‰) reveal that they did not undergo extensive fractional crystallization or fluid exsolution. Instead, their homogeneous zinc isotope compositions and distinct geochemical characteristics were inherited from their protoliths during partial melting. [ABSTRACT FROM AUTHOR]

The Late Mesozoic lithospheric mantle evolution of the Jiaodong Peninsula is crucial for understanding the destruction of the eastern North China Craton (NCC) and large-scale gold mineralization, but it still remains highly controversial. Here, we comprehensively compiled published Late Mesozoic mafic dyke magmatism data from the Jiaodong Peninsula to provide key constraints on the nature and evolution of the lithospheric mantle. Mafic dykes are widely emplaced in the Jiaodong Peninsula and have been divided into two groups (Jiaobei terrane and Sulu orogenic belt); they mainly comprise lamprophyre, dolerite, and gabbro. The ages of the mafic dykes in the Jiaobei terrane are predominantly between 120 and 125 Ma, and those of the Sulu orogenic belt are between 110 and 120 Ma. The Jiaobei and Sulu mafic dykes both have high contents of Mg and compatible elements (Cr, Ni), as well as low SiO2 content; they are characterized by arc-like mafic magma, including enrichment in Large Ion Lithophile Elements and Light Rare Earth Elements, depletion in High Field Strength Elements, high (87Sr/86Sr)i, and low εNd(t), implying a metasomatized lithospheric mantle source. However, the Jiaobei mafic dykes have relatively higher (87Sr/86Sr)i, lower εNd(t), and a larger range of (206Pb/204Pb)i, (208Pb/204Pb)i, and (207Pb/204Pb)i compared with the Sulu mafic dykes. The Jiaobei and Sulu mafic dykes exhibit Ba/Rb ratios of 1.29‒64.39 (average 29.3) and 6.61‒108.28 (average 33.1), respectively, indicating the presence of hornblende in the melts. The high Fe/Mn (>60) and Zn/Fe (>12) ratios of Jiaobei and Sulu mafic dykes indicate the mixed mantle source of peridotite and pyroxenite. But the content of pyroxenite in the mantle source of Jiaobei terrane is higher with wider range of Fe/Mn and Zn/Fe ratios. These features indicate the heterogeneity of the mantle sources of the mafic dykes in the Jiaobei and Sulu regions. It is suggested that both regions originated from the partial melting of hornblende-bearing peridotite, with the addition of more pyroxenite to the mantle source of the Jiaobei terrane compared to Sulu orogenic belt. The mafic dykes have the low Nb/Zr (Jiaobei: 0.024–0.229; Sulu: 0.030–0.166) and Th/Zr ratios (Jiaobei: 0.017–0.081; Sulu: 0.010–0.068), and the high Rb/Y (Jiaobei: 0.347–12.162; Sulu: 0.224–9.600) and low Nb/Y ratios (Jiaobei: 0.202–1.486; Sulu: 0.140–1.322). It implies that the mantle source area in both regions was metasomatized by subducted slab-derived fluids. The increase in (La/Yb)N and decrease in Hf/Sm implies carbonate metasomatism in both regions. In addition, some Jiaobei and Sulu mafic dykes have high Ti/Eu ratios, implying that the silicate metasomatism occurred in the mantle source of both regions. Based on the regional evolution, the lithospheric mantle source in the two regions beneath Jiaodong Peninsula experienced carbonated fluid metasomatism resulting from the subduction of the Palaeo-Asian Ocean plate beneath the northern NCC (ca. ~250 Ma), silicate melt-related metasomatism from subduction of the Yangtze Craton plate beneath the southern NCC (ca. 240‒220 Ma), and oceanic slab-derived fluid metasomatism from the subducted Palaeo-Pacific plate (at 180‒110 Ma). It is believed that the mantle source of Jiaobei terrane had undergone stronger carbonated fluid metasomatism and silicate melt-related metasomatism, compared to Sulu orogenic belt. Moreover, the continental fluid-related metasomatism only occurred in the Sulu orogenic belt. During the Late Mesozoic, the eastern NCC experienced large-scale lithospheric thinning, leading to upwelling of the asthenospheric mantle. The mafic dykes in Jiaobei and Sulu, show different geochemical features, were derived from partial melting of the metasomatized lithospheric mantle through upwelling of the asthenospheric mantle. [ABSTRACT FROM AUTHOR]

Located in the central part of the Central Asian Orogenic Belt, East Junggar represents one of the most important sites of juvenile crustal growth during the Phanerozoic. However, the mechanism of juvenile crustal growth during the Permian remains controversial. The Daheishan granites in the eastern segment of East Junggar are dated at ~292 Ma (Early Permian) and 269 Ma–267 Ma (Middle Permian). The Early Permian granites are coarse-grained with very high SiO2 (76.64 wt%–80.02 wt%), Al2O3 (10.72 wt%–12.96 wt%), and K2O/Na2O (1.27‒2.14), and low TiO2 (0.12 wt%–0.18 wt%), CaO (0.27 wt%–0.90 wt%), Mg# (25–32), and Sr/Yb (16–25). The Middle Permian granites are medium‒fine-grained with relatively high SiO2 (71.84 wt%–76.26 wt%), Al2O3 (11.26 wt%–13.00 wt%), and K2O/Na2O (0.53–1.54), and low TiO2 (0.17 wt%–0.21 wt%), CaO (0.37 wt%–3.20 wt%), Mg# (33–43), and Sr/Yb (5–9). These Permian granites display slightly positive whole-rock εNd(t) (+0.77 to + 1.04) and highly positive zircon εHf(t) (+7.3 to + 8.7) values, and low Ga/Al (2.04–2.55 < 2.6), P2O5 (0.02%–0.05% <0.14%), and zircon saturation temperature (690°C–749°C, take the median for each sample). Moreover, they display characteristic tetrad rare earth element patterns and non-CHARAC (CHArge-and-RAdius-Controlled) trace element behaviour, suggesting that the Daheishan granites are I-type granites that underwent both fractional crystallization (K-feldspar and plagioclase, e.g.) and crustal contamination prior to their emplacement. In combination with data from volcanic rocks in the Santanghu Basin, we infer that the Early Permian granitic magmas were derived from delamination of a thickened lithospheric mantle base and partial melting of pre-Permian arc components, while the Middle Permian granites formed during the subsequent stretching and thinning of the lithosphere. [ABSTRACT FROM AUTHOR]

The North Qinling Orogenic Belt (NQB) records the pivotal geological information for understanding the Palaeozoic evolution of the Qinling Orogenic Belt (QOB). Previous studies mainly focused on the subduction–collision process along the Shangdan suture zone before the Early Devonian. However, as the significant interim period between the Early Palaeozoic and Mesozoic orogeny, the Late Palaeozoic tectonic evolution of the NQB remains poorly understood. Fortunately, the Carboniferous magmatic rocks discovered this time provide substantial geological evidence for revealing the Late Palaeozoic tectonic history of the Qinling Orogenic Belt. This paper will provide a detailed analysis of zircon U–Pb ages, geochemical characteristics and Sr‐Nd‐Hf isotopic compositions of Carboniferous rocks. The Carboniferous magmatic rocks are categorized as highly differentiated S‐type granite and monzodiorite, formed at 350 ± 2.4 Ma and 353 ± 5.2 Ma, respectively. The granite shows weak peraluminous (A/CNK = 1.02–1.11) and shoshonite nature. Based on the isotopic composition and trace element characteristics, we propose that the Qinling Group paragneiss is the primary source of the Carboniferous granite. Monzodiorite is characterized by enriched LREEs and LILEs (Ba, K and Pb), depleted HFSEs (Th, Nb, Ta and Ti) and enriched Sr‐Nd isotopic composition. Monzodiorite magma source region consists of continental crustal material and lithospheric metasomatized mantle. Carboniferous magmatic rocks are the product of an extensional tectonic setting, which indicates the NQB tectonic regimes transition from compression to extension during the Carboniferous. [ABSTRACT FROM AUTHOR]

The Jiajika granitic- and pegmatite-type lithium deposit, which is in the Songpan-Garze Orogenic Belt in western Sichuan Province, China, is the largest in Asia. Previous studies have examined the geochemistry and mineralogy of pegmatites and their parental source rocks to determine the genesis of the deposit. However, the evolution of magmatic-hydrothermal fluids has received limited attention. We analyzed He–Ar–H–O isotopes to decipher the ore-fluid nature and identify the contribution of fluids to mineralization in the late stage of crystallization differentiation. In the Jiajika ore field, two-mica granites, pegmatites (including common pegmatites and spodumene pegmatites), metasandstones, and schists are the dominant rock types exposed. Common pegmatites derived from early differentiation of the two-mica granitic magmas before they evolved into spodumene pegmatites during the late stage of the magmatic evolution. Common pegmatites have 3He/4He ratios that vary from 0.18 to 4.68 Ra (mean 1.62 Ra), and their 40Ar/36Ar ratios range from 426.70 to 1408.06 (mean 761.81); spodumene pegmatites have 3He/4He ratios that vary from 0.18 to 2.66 Ra (mean 0.87 Ra) and their 40Ar/36Ar ratios range from 402.13 to 1907.34 (mean 801.65). These data indicate that the hydrothermal fluids were shown a mixture of crust- and mantle-derived materials, and the proportion of crust-derived materials in spodumene pegmatites increases significantly in the late stage of the magmatic evolution. The δ18OH2O–VSMOW values of common pegmatites range from 6.2‰ to 10.9‰, with a mean value of 8.6‰, and δDV–SMOW values vary from − 110‰ to − 72‰, with a mean of − 85‰. The δ18OH2O–VSMOW values of spodumene pegmatites range from 5.3‰ to 13.2‰, with a mean of 9.1‰, and δDV–SMOW values vary from − 115‰ to − 77‰, with a mean of − 91‰. These data suggest that the ore-forming fluids came from primary magmatic water gradually mixing with more meteoric water in the late stage of the magmatic evolution. Based on the He–Ar–H–O and other existing data, we propose that the ore-forming metals are mainly derived from the upper continental crust with a minor contribution from the mantle, and the fluid exsolution and addition of meteoric water during the formation of pegmatite contributed to the formation of the Jiajika superlarge lithium deposit. [ABSTRACT FROM AUTHOR]

Serpentinite-derived components play an important role in chemical cycling in subduction zones. However, it is difficult to identify recycled serpentinite in subarc mantle due to the overprinting of other slab components, and how serpentinite contributes to arc magmatism is poorly understood. Here we report Mo and Mg isotopic compositions of Early Paleozoic Qushiang arc mafic rocks in the East Kunlun orogen. The Qushiang mafic rocks have variable δ98Mo values of −0.50‰ to 0.78% and δ26Mg values of −0.31‰ to −0.05‰. These features, combining with arc-type trace element distribution patterns, enriched Sr Nd isotopes, and variable zircon Hf O isotopes, suggest the incorporation of different subducting components in their mantle source. Some mafic rocks show high δ98Mo values together with low Mo/Ce ratios and enriched Sr Nd isotopes, suggesting the contribution of subducted sediment (SSD)-derived melts. Additionally, light Mo isotopes are also identified in mafic rocks, which are closely related to depleted Sr Nd isotopes. These features are mainly inherited from the subducted dehydrated altered oceanic crust (SAOC)-derived melts. More importantly, the coexisting and significantly high δ26Mg and δ98Mo values of these rocks could not be explained by the SSD or SAOC components, but require serpentinite components in the subarc mantle source. Our study reveals that combined Mo and Mg isotopic studies are potential tools for tracing serpentinite recycling, and provides new insight into the mechanisms by which different subducting components contribute to arc magmatism. [ABSTRACT FROM AUTHOR]

Syn-exhumation and post-collisional mafic magmatism in continental collision orogenic belts may provide insights into the nature of orogenic lithospheric mantle and recycled continental components in continental subduction zones. Lithium and its isotopes have emerged as potentially valuable tools for shedding light on the origin of these magmas, given the contrast Li contents and isotopic compositions between the subducting continental crust and the mantle. Here, we present high-precision Li isotopes data for representative orthogneiss, continental eclogite, syn-exhumation and post-collisional mafic magmatic rocks from the North Qaidam orogen. The syn-exhumation mafic magmatic rocks have relatively higher Li contents (26.5-50.0 ppm) and lower δ7Li values (-1.01%o-1.48%o) than those of the post-collisional mafic magmatic rocks (Li = 11.1-22.7 ppm, δ7ϋ = 1.20%-3.38%), which are comparable to those of orthogneiss and continental eclogite, respectively. Dehydration and melting modelling results show that these mafic magmatic rocks have similar Li contents and δ7Li values to the continental eclogite- and orthogneiss-derived melts but are different from their derived fluids. Monte Carlo simulation for Li-Nd isotopes suggests the syn-exhumation and post-collisional mafic rocks could be derived from an enriched mantle source that contains ~3-8% continental crustal components dominated by the orthogneiss and continental eclogite. The calculated results are consistent with the results from the previous study simulated by trace elements. Therefore, our results highlight Li isotopes as a potential tool to trace the nature of the continental crustal components recycling in continental subduction zones. [ABSTRACT FROM AUTHOR]

The origin of granitic rocks from the South Qilian orogenic belt is of great significance for understanding the continental tectonic framework of Western China. Currently, scholars have different opinions on the tectonic evolution of the South Qilian. Huashigou granite, which exhibits multiple intrusive episodes, is a suitable example for studying the tectonic evolution of the South Qilian. New zircon U–Pb ages and the whole-rock elemental and Sr–Nd–Hf–O isotopic compositions of Huashigou granitic rocks are presented here to investigate their petrogenesis and discuss the tectonic implications for the evolution of the South Qilian orogenic belt. LA-ICP-MS zircon U–Pb dating yielded crystallization ages of 368.7 ± 3.5 Ma, 261.5 ± 0.63 Ma, and 262.2 ± 1.4 Ma for granodiorites from the Hua1 pluton, quartz diorites from the Hua2 pluton, and porphyritic tonalites from the Hua4 pluton, respectively. Late Devonian granodiorites from the Hua1 pluton belonged to the metaluminous calc-alkaline series and were characterized by an enrichment in LREEs, a depletion in HREEs, negative Eu anomalies, and Sr/Y ratios of 9.17 to 11.67. They showed (87Sr/86Sr)i ratios of 0.712356 to 0.71195, εNd(t) values of −6.56 to −6.14, and an εHf(t) value of −2.06. Middle Permian granitic rocks mainly consisted of quartz diorites and porphyritic tonalites, which are part of the metaluminous tholeiitic series and weakly peraluminous tholeiitic series, respectively. Quartz diorites from the Hua2 pluton were characterized by an enrichment in LREEs, depletions in HREEs and HESEs, weak negative Eu anomalies, and Sr/Y ratios of 13.25 to 14.79. They showed (87Sr/86Sr)i ratios of 0.705905 to 0.705971, εNd(t) values of +0.78 to +0.82, and a δ18OV-SMOW value of 12.4‰. Porphyritic tonalites of the Hua4 pluton were characterized by an enrichment in LREEs, depletions in HREEs and HESEs, weak negative Eu anomalies, and Sr/Y ratios of 9.22 to 12.74. They showed (87Sr/86Sr)i ratios of 0.719528, εNd(t) values of −8.57, and a δ18OV-SMOW value of 11.8‰. We can conclude that Late Devonian granodiorites were derived from the partial melting of enriched and shallow-depth crustal materials, whereas Middle Permian granitic rocks were formed by the delamination of a thickened lower crust after the closure of the Paleo-Tethys Ocean, which caused the underplating of mantle-derived basaltic magma, inducing the partial melting of the lower crust at different depths. Our results show that there were at least two important stages of compressional and extensional tectonic switches in the South Qilian orogenic belt during the Late Paleozoic Era, and the evolution of Altyn Tagh–Qilian–North Qaidam had evident stages. [ABSTRACT FROM AUTHOR]

Crustal rocks in collisional orogens often underwent the metamorphic transition from dehydration to anatexis in response to an increase of geothermal gradients, but it remains obscure how the two types of metamorphism influenced each other. This issue can potentially be addressed by an integrated study of mineralogy and geochemistry for tourmaline in protoliths and their anatectic products. In this paper, we present new results from comprehensive analyses of major-trace elements and B isotopes in tourmaline together with whole-rock Sm–Nd isotopes in well-characterized metapelites and leucocratic dikes from the Himalayan orogen. The leucocratic dikes show whole-rock ε Nd (t) values of −15.7 to −15.4, falling within an ε Nd (t) range of −17.7 to −13.8 for the metapelites. In the metapelites, metamorphic tourmaline (Tur-M) is dravitic and has relatively low δ11B values of −12.0 to −9.0‰. As the metamorphic grade increases, the δ11B values of Tur-M decrease, which is linked to progressive metamorphic dehydration. In the leucocratic dikes, three types of tourmaline are identified by different petrological and geochemical criteria. The tourmaline cores (Tur-LC) are schorlitic and have relatively high δ11B values of −8.7 to −7.7‰, and this type is ascribed to an anatectic origin. The tourmaline rims (Tur-LR) corroding the Tur-LC are dravitic and have relatively high δ11B values of −9.6 to −7.6‰, and this type is attributed to a fluid origin. Another type of anatectic tourmaline (Tur-L) occurs as grains with homogeneous oscillatory zoning that are dravitic and have slightly higher δ11B values of −10.4 to −5.9‰. The anatectic Tur-LC in the leucocratic dikes has higher δ11B values than the metamorphic Tur-M in the metapelites. We attribute this difference to the addition of external fluids with high δ11B values to the metapelite source at the overlying crustal levels. The influxed fluids most likely originated from metamorphic dehydration of lithologically similar metapelites at deeper crustal levels, as evidenced by the Mg-rich characteristics of Tur-L and Tur-LR. The metamorphic fluids would ascend into shallow crustal levels through faults and shear zones, which could not only trigger fluid-fluxed (hydration) melting of the metapelites but also result in fluid activity in later stages. This is further verified by phase equilibrium modelling and model calculation of B geochemical behavior during both metamorphic dehydration and partial melting. On this basis, a spatiotemporally coupled dehydration-hydration melting mechanism is proposed to link the early dehydration metamorphism to the later anatectic metamorphism in the collisional orogen. [ABSTRACT FROM AUTHOR]

Ancient environments have been mostly reconstructed with exogenous records, yet the potential constraints from endogenous archives were less emphasised. It has been well known that the outer- and inner-spheres of the planetary Earth are naturally linked and/or interplayed each other among geospheres. As stable isotopes of the meteoric water are globally dependent upon precipitating environments, rocks and/or minerals hydrothermally altered by the meteoric water can thus imprint environmental information of continental settings. These valuable clues, however, have been intuitively and/or qualitatively inferred up to now. On the basis of an innovative procedure recently proposed for dealing with thermodynamic re-equilibration of oxygen isotopes between constituent minerals and water from fossil hydrothermal systems, ancient meteoric waters are theoretically inverted from the early Cretaceous post-collisional granitoid and Triassic gneissic country rocks across the Dabie orogen in central-eastern China. The initial oxygen isotopes of ancient meteoric water (i.e., $\delta ^{18}O_W^i$ value hereafter) range from −11.01 ± 0.43 (one standard deviation, 1SD) to −7.61 ± 0.07‰ in this study, yet systematically and/or statistically deviating from modern local precipitation. These imply that either palaeoclimate could be colder than the present at least during the early Cretaceous or palaeoaltimetry has geographically varied across the Dabie orogen since the Triassic. Moreover, the lifetime of fossil hydrothermal systems is kinetically quantified to less than 1.2 million years (Myr) for the concurrent lowering of oxygen isotopes of hydrothermally altered rock-forming minerals through the surface-reaction oxygen exchange with ancient meteoric waters herein. Our results thus suggest that palaeoenvironments of the continental orogen can be scientifically and methodologically unearthed from endogenous archives and theoretical inversion of $\delta ^{18}O_W^i$ values can be quantitatively applied beyond the Dabie orogen. [ABSTRACT FROM AUTHOR]

Permian mafic dikes crop out widely within Beishan area in the southernmost Central Asian Orogenic Belt (CAOB). These mantle-derived products provide important clues for elucidating the genesis and geodynamic setting of Permian magmatism. The mafic dikes within the Beishan area display zircons U–Pb ages of 281 ± 4 Ma. Characterized by low SiO2 (44.88–47.73 wt.%) and high Mg# values (62.2–68.6), the type 1 dikes are relatively depleted in light rare earth elements (LREEs; (La/Yb)n = 0.72–1.43) but enriched in large ion lithophile elements (LILEs). They show high positive εNd(t) values (6.6–8.5) with a range of (87Sr/86Sr)i (0.703477–0.705789) ratios. In contrast, the type 2 dikes have higher SiO2 content (47.47–51.13 wt.%) and lower Mg# (40.9–63.0). They are enriched in LREEs ((La/Yb)n = 1.79–5.02) and LILEs, and have lower εNd(t) values (3.8–7.4) with a variable range of (87Sr/86Sr)i (0.702873–0.706949) ratios. Thus, the type 1 dikes resulted from lower degrees of fractional crystallization and contamination than the type 2 dikes. Considering the LILEs and Pb enrichments, high field strength elements depletions, and high Ba/Th (86–460) ratios, the mantle source was metasomatized by subduction-related fluids. These dikes should be derived from high degrees (>20%) of partial melting of a Sr–Nd isotope-depleted, phlogopite-bearing spinel lherzolite lithospheric mantle according to their high Rb/Sr (0.04–0.24), low Ba/Rb (0.9–3.3), low La/Sm, and constant Sm/Yb ratios in addition to Sr–Nd depletion. Combined with the coeval evidence of regional geology and novel tectonic discriminate diagrams, we suggest that the mafic dikes in Beishan area formed in arc-related setting rather than intracontinental setting during the Permian. The metasomatized lithospheric mantle by subduction-related fluids were heated by upwelling asthenosphere mantle triggered by the slab roll-back, resulting in the formation of the parental magma of the mafic dikes. [ABSTRACT FROM AUTHOR]

The paper presents data on the U–Pb chronology of detrital zircon grains and radiogenic isotopic composition (87Sr/86Sr, ɛNd) from the Proterozoic clastic successions of the Garhwal‐Kumaon Lesser Himalaya representing the extended northern Indian cratonic margin, NW India. The Proterozoic Lesser Himalayan Basin in Garhwal‐Kumaon Himalaya is divided into two sectors, namely, Inner Lesser Himalaya (ILH) and Outer Lesser Himalaya (OLH) by a tectonic boundary, namely the Tons Thrust (TT). Age distribution from inner and outer sectors of the Lesser Himalaya shows that the U–Pb chronology of most of these zircons provides Palaeoproterozoic (between 1.6 and 1.8 Ga) to Neoproterozoic (800 Ma) ages. The age data suggest sedimentation of the Rautgara Formation (Damtha Group) of ILH continued till the Neoproterozoic (~850 Ma), which was earlier regarded as ≤1.6 Ga. Tracking the detrital U–Pb zircon ages in the near adjacent cratonic parts point towards Aravalli Orogen as the major source region. Whole‐rock ƐNd(0) values for ILH rocks range from −37.6 to −14.6 and for OLH it ranges from −19.6 to −6.7. More negative ƐNd values along with dominance of Neoarchean‐Palaeoproterozoic ages in ILH indicates supply from more evolved protolith or recycled sources and less negative ƐNd values with major Neoproterozic zircon ages from OLH supports for less evolved source rock. The change from more negative ƐNd to less negative ƐNd values progressively upward the stratigraphy can be due to a shift in source with time. Both U–Pb zircon and ƐNd supports for a continuous sedimentation model, rule out the presence of ~500 Ma unconformity within the LH and argues for separate evolution of the Lesser Himalayan Basin on the trailing edge of the extended north Indian craton in "Columbia" configuration. [ABSTRACT FROM AUTHOR]

This article presents the results of U–Pb (ID-TIMS) geochronological, geochemical, and Sm–Nd isotopic-geochemical studies of metavolcanic rocks of the Djagdagle Formation, which belong to the key elements of the Bureya continental massif. It was established that the age of metavolcanic rocks of the Djagdagle Formation is 217 ± 7 Ma and corresponds to the Late Triassic. This fact contradicts the traditional ideas, according to which the Djagdagle formation is the Early Precambrian in age. The results of Sm–Nd isotope studies of the metavolcanic rocks indicate the melting of rocks of continental crust with Paleoproterozoic model ages during the formation of initial melts. The new geochronological data and previously published data allow us to distinguish at least two stages of magmatic activity in the Triassic within the northwestern part of the Bureya massif: ~243 and 219–201 Ma. On the basis of synchronous of Neoproterozoic, Early Paleozoic, Late Paleozoic, and Early Mesozoic magmatic events in the geologic history of the Bureya and Songnen–Zhangguangcai Range massifs, an assumption about their common geological history at least since the Late Neoproterozoic has been proposed. The close spatial position of metavolcanic rocks of the Djagdagle Formation and the Mongol–Okhotsk Orogenic Belt, their Late Triassic age (217 ± 7 Ma), and geochemical features allow us to link the formation of initial melts of metavolcanic rocks of this formation with within-plate magmatism in the rear part of subduction zone of the Mongol–Okhotsk Ocean beneath the northern (in modern coordinates) margin of the Bureya continental massif. [ABSTRACT FROM AUTHOR]

The well-preserved Ashele subseafloor replacement-style volcanogenic massive sulfide (VMS) deposit in the Central Asian Orogenic Belt comprises two stages of Cu mineralization, i.e., early massive sulfides dominated by colloform and euhedral pyrite intergrown with chalcopyrite and sphalerite, which were replaced by late vein-dominated chlorite-chalcopyrite assemblages. In this study, a combined systematic Fe, B, and S isotope investigation was first applied to investigate the sulfide precipitation processes and the relative proportion of fluid sources in different alteration and mineralization stages of the Ashele deposit. Boron isotopes of Mg-rich tourmaline (δ11B from -5.57‰ to -2.73‰, average (avg.) -4.23‰) indicate significant seawater (∼19%) participated during the formation of massive sulfides. A two-component mixing model is used to estimate the contribution of seawater and igneous sulfur to the total sulfur budget, and the results show the increasing contribution of magmatic sulfur from the early (35%) to late (76%) stages. In addition, δ56Fe values of pyrite gradually increase from the massive ore (-0.46‰ to -0.02‰, avg. -0.24‰), quartzpyrite (-0.09‰ to 0.07‰, avg. -0.01‰), chlorite-chalcopyrite-quartz-pyrite (0‰ to 0.21‰, avg. 0.08‰) to the quartz-sericite zone (-0.02‰ to 0.29‰, avg. 0.14‰), which is likely related to the different extent of isotopic exchange and formation temperature, and could be used in the exploration of VMS systems. The new two-stage ore-forming model shows that in the early stage, rapid mixing of hydrothermal fluid from underlying magma chamber with abundant cold seawater led to rapid deposition of pyrite and associated Cu mineralization under relatively oxidized condition, and long-term hydrothermal activities in relatively closed systems would promote the formation of upper massive ores, which resulted in an equilibrium system between pyrite, chalcopyrite, and associated fluid with wide ranges of δ56Fe in pyrite (-0.46‰ to -0.02‰) and chalcopyrite (-1.56‰ to -0.49‰). The late hydrothermal activities in relatively open system would contribute to stringer sulfides or stockworks underlying the massive ore in relatively reduced conditions with heavier Fe isotope compositions in pyrite (-0.09‰ to 0.29‰) and chalcopyrite (-0.60‰ to - 0.04‰). Overall, our study demonstrates that the coupling of B, Fe, and S isotopes could be a useful tool to indicate long-term subseafloor infilling and replacement processes for subseafloor replacementtype VMS deposits, which are the prerequisite to form large-tonnage VMS deposits. [ABSTRACT FROM AUTHOR]

Tourmaline and gold mineralization form an association in the Bakoshi-Gadanya (BAG) Goldfield on the northern West Nigerian Subshield, located in the southern Trans-Saharan Orogenic Belt of West Africa, although the cogenicity of this association remains untested. In this study, we report the results of an integrated study of the boron isotopic and major- and trace-elemental compositions of BAG tourmalines, from which we infer the nature and origin of the hydrothermal parent fluids and their role in the associated gold mineralization. Tourmalines in the BAG Goldfield are of four types: altered granite-related (Tur I), wallrock-hosted (Tur II), Gadanya Tourmalinite (Tur III) and Shanono Tourmalinite (Tur IV). The tourmalines mainly belong to the alkali group with dravite (i.e., Mg-rich) compositions. The MgFe −1 and □Al(NaR) −1 exchange vectors are the dominant substitution mechanisms for all BAG tourmalines with contributions from deprotonation AlO[R(OH)] −1 substitutions. Except for Tur I, which is enriched in Rb (0.02–21.9 ppm) and Cs (0.01–0.63 ppm), due to high fluid-rock reaction, the BAG tourmalines are enriched in Cr (2.0–3908 ppm), Ni (5.0–222 ppm), Co (0.05–27.4 ppm), Sr (41.8–3031 ppm), Sc (1.6–281 ppm), V (32.0–701 ppm), Al (0.01–0.35 apfu), Fe (0.59–1.47 apfu), and Mg (0.67–2.43 apfu), suggesting metasedimentary-derived components. Boron isotopes display bimodal populations from −16.8 to −12.0 ‰ (Tur II to IV) and from −23.0 to −19.0 ‰ (Tur I). We propose that greenschist to amphibolite facies metamorphism during the Pan-African Orogeny devolatilized country-rock metapelites and produced a metamorphic-hydrothermal fluid responsible for BAG tourmalinization. These metamorphic-derived Tourmalines show no relationship to the magmatic-hydrothermal fluid derived BAG gold ore. Our results show that the BAG tourmalines may not serve as indicator minerals in exploration for gold mineralization in the BAG Goldfield in northern West Nigerian Subshield. • Tourmalines from the Bakoshi-Gadanya area mainly alkali type and dravitic compositions • Metamorphic fluids led to tourmalinization • Tourmalines elemental composition contrast the gold fluid chemistry [ABSTRACT FROM AUTHOR]

The widely distributed Late Hercynian–Indosinian granites in the West Qinling Orogenic Belt are keys to better understand the tectonic–magmatic evolution of the West Qinling Orogenic Belt. In this paper, granitoids from the Zhacanggou area of Guide Basin in the western section of the West Qinling Orogenic Belt were studied on petrography, geochemistry, zircon U–Pb dating, and Lu–Hf isotopes. Zircon U–Pb dating yield granitoids in the Zhacanggou area were emplaced at 228.3 ± 4.4 Ma, 265.2 ± 2.2 Ma and 277.8 ± 2.5 Ma, respectively. The whole-rock geochemical compositions of these granitoids belong to the weakly peraluminous calc-alkaline to metaluminous high-K calc-alkaline series, and exhibit different degrees of negative Eu anomalies, loss of high-field strength elements (Nb, P and Ti), and enrichment of large ion lithophile elements (Rb, Th, U and Sr). The ε Hf (t) values of Early–Middle Permian and Late Triassic granitoids range from −12.0 to 5.3 and –10.6 to −5.0, and corresponding two-stage model ages (T DM2) of 956 to 2051 Ma and 1581 to 1936 Ma, respectively. A summary of geochronology for granitoids formed in the West Qinling Orogenic Belt during the Late Hercynian–Indosinian indicating magmatic activities concentrated in the Late Triassic (210–230 Ma) and Permian–Middle Triassic (235–277 Ma). These granitoids were both formed by partial melting of ancient crust, which then mixed with enriched lithospheric mantle, and the former has a higher mantle contribution than the latter. The early granitoids were associated to northward subduction of the Mianlue oceanic slab, while the late granitoids were formed in the transition from collision to extension. • Two stages of magmatic activities (210–230 and 235–277 Ma) were widely developed in the West Qinling Orogenic Belt. • Granitoids were both formed by partial melting of ancient basalt, and then mixed with enriched lithospheric mantle. • Permian–Middle Triassic granitoids are related to subduction of the Mianlue Ocean slab. • Late Triassic granitoids were formed in the transition from collision to extension. [ABSTRACT FROM AUTHOR]

• Ultrapotassic lavas show lower δ41K and higher δ56Fe values than calc-alkaline lavas. • The low-δ41K values reflect the incorporation of deeply subducted sediments. • The high-δ56Fe signatures imply pyroxenite sources. • The interaction between sediment-derived melts and peridotites forms the pyroxenites. Ultrapotassic volcanism commonly occurs following calc-alkaline magmatism in continental collisional tectonic zones, but some key aspects of this transition remain ambiguous. In particular, there are uncertainties regarding the changing nature of the mantle source and the contribution of recycled continental material during the petrogenesis of ultrapotassic igneous rocks. Here, we show that the calc-alkaline to ultrapotassic transition in magmatism in Western Anatolia (Türkiye) during the past 55 Ma was associated with conspicuous shifts in the K and Fe isotope compositions of the bulk eruptive rocks. The ∼52–17 Ma transitional (tholeiitic to calc-alkaline) and calc-alkaline rocks show low δ56Fe (0.05 ± 0.07 ‰, 1SD) and high δ41K values (from –0.41 ‰ to 0.00 ‰), relative to the overall higher δ56Fe (0.16 ± 0.05 ‰, 1SD) and lower δ41K values (from –0.32 ‰ to –0.55 ‰) of the ∼19–15 Ma shoshonitic-ultrapotassic rocks in this area. The low δ41K values observed in the shoshonitic-ultrapotassic rocks are interpreted to reflect incorporation of potassium from deeply subducted recycled continental crust and the heavy Fe isotope signatures of these rocks imply a pyroxenite source. The rapid onset and short duration of eruption of the shoshonitic-ultrapotassic rocks is consistent with formation of phlogopite-pyroxenite veins within the peridotite mantle during slab rollback and/or breakoff. These veins were then rapidly and completely consumed by upwelling hot asthenospheric mantle. [ABSTRACT FROM AUTHOR]

[Display omitted] • The Wutuogou Ag-Pb-Zn deposit formed in the Late Triassic (ca. 210 Ma). • The majority of silver is hosted by pyrargyrite, freibergite, and freieslebenite. • Silver precipitation was facilitated by temperatures and f S 2 decreases. • A magmatic-hydrothermal origin is defined for the Wutuogou Ag-Pb-Zn deposit. The Wutuogou Ag-Pb-Zn deposit, a newly discovered vein-type deposit, is located in the Eastern Kunlun Orogenic Belt (EKOB), northwestern China. The vein-type Ag-Pb-Zn ore bodies are hosted in Middle Triassic granodiorite and monzogranite and are characterized by high-grade Ag, Pb, and Zn (average Ag: 293 g/t, Pb: 3.00 %, Zn: 2.85 %). Three paragenetic stages have been recognized: quartz + pyrite (Py-1) + arsenopyrite (stage I), pyrite (Py-2) + sphalerite + chalcopyrite + tetrahedrite + quartz (substage II-1), galena + pyrargyrite + freibergite + freieslebenite + quartz + calcite (substage II-2), and quartz + calcite (stage III). Except for Ag-bearing minerals (pyrargyrite, freibergite, and freieslebenite), invisible silver is also present in pyrite (1.91–165 ppm), sphalerite (3.86–8806 ppm), and galena (up to 0.21 wt%). The calcite is closely associated with sulfides in substage II-2 and yields a U-Pb age of 210 ± 7 Ma (MSWD = 2.7), which represents the ore-forming age (lower limit). Py-1 displays higher As contents and lower Co contents than those of Py-2, indicating a decrease in temperature from stage I to stage II. In addition, the Fe/Zn mass ratios (0.025–0.075) of sphalerite estimate the fluid temperature for substage II-1 of 246–284 °C, whereas the Ag/(Ag + Cu) and Zn/(Zn + Fe) mole ratios of freibergite estimate the fluid temperature for substage II-2 of 140–270 °C, further indicating the decrease of temperature from stage I through substage II-1 to substage II-2. Mineral assemblages of pyrite-chalcopyrite-tetrahedrite in substage II-1 and Ag-sulfosalts in substage II-2 suggest a decrease in sulfur fugacity (f S 2). Both the decrease in f S 2 and cooling of the mineralizing fluids facilitate silver precipitation. The heterogeneous compositions of the freibergite and the Ag zonation in sphalerite (Sp-1) resulted from retrograde solid-state reactions that redistributed Ag through microscale exsolution. The δ 34S values (+5.49 to +7.78 ‰) of the sulfides and the low Zn/Cd ratios (107–195) of sphalerite indicate a felsic magma source for the ore-forming materials. Therefore, we concluded that the Wutuogou Ag-Pb-Zn deposit corresponds to a medium- to low-temperature magmatic-hydrothermal deposit associated with Late Triassic magmatism in the Eastern Kunlun Orogenic Belt (EKOB). [ABSTRACT FROM AUTHOR]

Mafic arc igneous rocks with oceanic crust-derived fluids in their mantle sources generally show heavy Mo isotope compositions. However, these rocks may exhibit variable Mo isotope compositions due to involvement of seafloor sediments under different redox conditions. Thus, it is intriguing how Mo isotope recycles with sediment subduction and how Mo isotope fractionation occurs during this process. Here we report Mo isotope data for Paleozoic mafic arc igneous rocks from the Qinling-Tongbai orogenic belt in Central China. The Qinling mafic rocks have δ98Mo values of −0.03 to 0.40‰, and the Tongbai mafic rocks have δ98Mo values of −0.26 to 0.17‰. These values are considerably higher than the normal mantle values of −0.20 ± 0.01‰. In combination with low Mo/Ce ratios, enriched Sr Nd isotope compositions, and high melt-mobile incompatible trace element contents for these rocks, the high δ98Mo values suggest that anoxic sediment-derived melts with heavy Mo isotopes were incorporated by oceanic subduction into the mantle sources. The high δ98Mo values of the mafic rocks indicate the limited Mo isotope fractionation during subduction of the anoxic sediment. This inference is further verified by modeling of Mo isotope fractionation under reducing conditions in the subduction zone. In this regard, Mo isotopes can be used to identify the recycling of sediments in different types and thus provide geochemical constraints on the redox conditions of oceanic subduction zones. [ABSTRACT FROM AUTHOR]

Copper and iron isotopic signatures in sulfide and silicate minerals are important genetic indicators in magmatic sulfide deposits. Kalatongke is a large‐scale magmatic Cu‐Ni sulfide deposit in the Central Asian Orogenic Belt, and one that experienced multiple stages of magmatism and contamination. It is an ideal deposit in which to study Cu‐Fe isotopic fractionation during multiple stages of magmatism and sulfide mineralization processes. The Kalatongke sulfide orebodies are hosted by three small mafic intrusions in which pyroxene and sulfides (pyrrhotite, pentlandite, and chalcopyrite) are the most common Fe‐rich minerals, and chalcopyrite is the dominant Cu‐rich mineral. Sulfide liquid and silicate melt ▵56FeSul‐Sil (0.03–0.19‰) and ▵65CuCcp‐Sil (−0.78–0.74‰) values are indicative of non‐equilibrium fractionation. Most of the Cu isotope compositions in the sulfide ores at Kalatongke can be modeled as subduction‐ metasomatized, oxidized mantle source‐derived silicate melt (initial δ57Fe = 0.15‰, δ65Cu = −0.07‰) that underwent lower crustal contamination, and then reacted with silicate melt, having an R factor of 100–1,000. Rapid silicate melt and sulfide liquid Fe isotope exchange and re‐equilibration between chalcopyrite and pyrrhotite in the massive ores is reflected in the similarity of their δ56Fe values. Sulfide in disseminated ores shows a range of Fe isotope ratios, influenced by the proportions of monosulfide solid solution (MSS) and intermediate solid solution (ISS) formed. Copper isotopes can be utilized to characterize crustal contamination and silicate melt‐sulfide liquid interaction, while the Fe isotope ratios of sulfide minerals record sulfide liquid segregation and evolution in magmatic sulfide deposits. Key Points: Sulfide δ65Cu and δ56Fe signatures reflect crustal contamination, sulfide and silicate melt reactions, and sulfide liquid segregationCopper isotopes can record the source and crustal contamination, sulfide liquid and silicate melt reaction, and sulfide segregationVarious range of sulfide minerals Fe isotopes influenced by the segregation of MSS and ISS and their ratios [ABSTRACT FROM AUTHOR]

[Display omitted] • Mo isotopes variation in both the two Mo deposits may be controlled by Rayleigh and equilibrium fractionation. • The Taihua Soupergroup and the Xiong'er Group would be the main contributor of Mo metal for the Paleoproterozoic Mo mineralization. • The mantle with light isotopically Mo involved into the Mo Paleoproterozoic mineralization in Qinling orogenic belt. Longmendian and the Zhaiwa are the two oldest Mo deposits in the Qinling orogenic belt, China, which is one of the most important Mo provinces in the world with numerous and diverse types of Mo deposits that experienced multistaged mineralization. Here we investigated Mo isotope compositions in molybdenite and rocks from the Longmendian and the Zhaiwa Paleoproterozoic Mo deposits to link Mo isotopes to the sources of Mo metal. The significant Mo isotope variation in the Longmendian and the Zhaiwa Mo deposits (δ98Mo = −0.51‰ to + 1.01‰ and −0.37‰ to +0.53‰, respectively, relative to NIST-3134) may be controlled by Rayleigh and equilibrium fractionation. The different distributions of Mo isotope compositions of molybdenite in the two deposits may be caused by the physiochemical differences in ore-forming systems. The high Mo content of the Taihua Supergroup and the Xiong'er Group, combined mean values of Mo isotopes between molybdenite and whole rocks suggested that the two stratigraphic units would be the main contributor of Mo for the Paleoproterozoic Mo mineralization that mixed with small proportions of isotopically lower values of the mantle. [ABSTRACT FROM AUTHOR]

The Altun orogenic belt is situated along the northern boundary of the Tibetan Plateau. In this study, we present an analysis of the ore deposit, mineral composition, and carbon isotope signatures of the Tugeman graphite deposit within the Altun orogenic belt. The graphite in the Tugeman graphite deposit occurs within graphite-bearing schists and marble. Graphite enrichment is observed in the ductile shear zone. The carbon isotope values of graphite range between −18.90‰ and −10.03‰ (with an average value of −12.70‰). These values differ significantly from those observed in organic matter and marine carbonates, suggesting the occurrence of a mixing process involving reduced carbon fluid derived from biological organic material during regional metamorphism as well as a potential influx of oxidized carbon fluid from external sources. In addition, the metamorphic temperature of Tugeman graphite calculated from Raman spectroscopy is between 494 °C and 570 °C, which indicates that the disordered material is transformed from greenschist-amphibolite facies metamorphism to moderate-crystalline graphite. Combining the geological and carbon isotope characteristics of the Tugeman graphite deposit, we argue that the Tugeman graphite deposit is a regional metamorphic graphite deposit of biogenic origin, and during the late stage of metamorphism, it underwent interaction with fluids. [ABSTRACT FROM AUTHOR]

[Display omitted] • The peak of high grade metamorphism has been constrained to occur at 566–565 Ma, proving the Jiamusi-Kuunga-Pinjarra linkage. • The continental crust of the Jiamusi Block is featured by a progressive rather than episodic growth pattern. • Diverse forms of crustal growth have been defined in an accretionary orogen. There is a considerable debate as to when and how the continental crust has evolved to its present state. Existing studies of crustal evolution have focused on large cratons, whereas microcontinents within accretionary orogenic belts have been conspicuously neglected. The controversial definition of tectonic origins and lack of Precambrian basement rocks of microcontinents, lead to an equivocal issue of their secular crustal evolution processes. Here we present zircon U-Pb ages and Hf-O isotopes, as well as whole-rock elemental and Sr-Nd-Pb-Hf isotopic data for the newly discovered Neoproterozoic orthogneisses from the Jiamusi Block of NE China in the easternmost Central Asian Orogenic Belt (CAOB). LA-ICP-MS U-Pb dating of zircons from the orthogneisses recorded two episodes of magmatism at 896–886 Ma and 752–726 Ma. Combined with zircon Hf-O isotopes and REE patterns, the peak of the late Pan-African metamorphism is proved to occur at 566–565 Ma, demonstrating the linkage between the Jiamusi Block and the Kuunga-Pinjarra interior orogen of East Gondwana. In conjunction with compiled zircon U-Pb-Hf isotopic data of Neoproterozoic-Mesozoic granitoids, a new crustal evolution model has been established for the Jiamusi Block, which defines a continuous rather than an episodic crustal growth pattern during the Neoarchean to Neoproterozoic, as well as four stages of crustal reworking at 940–880 Ma, 780–660 Ma, 560–460 Ma, and 340–240 Ma. The enhanced and reduced rates of crustal growth during the progressive period are related to the assembly-breakup and collision phases of supercontinent cycles, respectively. Our study along with previous researches on eastern CAOB not only highlights that the Phanerozoic accretionary orogen underwent diverse forms of crustal growth with most of the continental crust formed during the Precambrian, but also provides an example to show the heterogeneity of the lower continent and the complexity of global secular crustal evolution. [ABSTRACT FROM AUTHOR]

The Xinghongpu Formation is very important for understanding the Devonian tectonic evolution of the South Qinling orogenic belt. Geochemical, detrital zircon U-Pb-Hf isotopic studies were carried out on the Late Devonian metasedimentary rocks of the Xinghongpu Formation to constrain the depositional age, the provenance, and the tectonic setting. The detrital zircon U-Pb dating results revealed that the depositional age of the Xinghongpu Formation of the Late Devonian was not earlier than 363.2 Ma. The whole-rock geochemistry suggested that (1) this suite of metasedimentary rocks was mainly derived from quartzose sediments of mature continental provenance, with a small contribution from mafic and intermediate igneous provenance, and (2) the metasedimentary sandstone of the Xinghongpu Formation from the Late Devonian was deposited in an active continental margin to continental arc setting. The detailed detrital zircon U-Pb dating showed that the age spectra of detrital zircon could be divided into four groups: (1) 416–480 Ma, accounting for about 23%; (2) 740–850 Ma, accounting for about 19%; (3) 889–1017 Ma, accounting for about 19%; and (4) 1072–1146 Ma, accounting for about 12%. It also contained a group of Early Proterozoic zircons. The age and Hf isotope of the detrital zircons suggested that the clastic sediment deposited in the Xinghongpu Formation mainly came from the South Qinling Orogenic Belt and the North Qinling Orogenic Belt. The detrital zircon Lu-Hf isotopes indicated that most zircons were the products of the ancient crustal remelting, and the mantle-derived magmatic sources contributed to the provenance. The Xinghongpu Fm. formed in an oceanic basin in a continental margin environment with arc systems. [ABSTRACT FROM AUTHOR]

Cretaceous‐Miocene sedimentary rocks in the Nepalese Lesser Himalaya provide an opportunity to decipher the timing of India‐Asia collision and unroofing history of the Himalayan orogen, which are significant for understanding the growth processes of the Himalayan‐Tibetan orogen. Our new data indicate that detrital zircon ages and whole‐rock Sr‐Nd isotopes in Cretaceous‐Miocene Lesser Himalayan sedimentary rocks underwent two significant changes. First, from the Upper Cretaceous‐Palaeocene Amile Formation to the Eocene Bhainskati Formation, the proportion of late Proterozoic‐early Palaeozoic zircons (quantified by an index of 500–1200 Ma/1600–2800 Ma) increased from nearly 0 to 0.7–1.4, and the percentage of Mesozoic zircons decreased from ca. 14% to 5–12%. The whole‐rock 87Sr/86Sr and εNd(t = 0) values changed markedly from 0.732139 and −17.2 for the Amile Formation to 0.718106 and −11.4 for the Bhainskati Formation. Second, from the Bhainskati Formation to the lower‐middle Miocene Dumri Formation, the index of 500–1200 Ma/1600–2800 Ma increased to 2.2–3.7 and the percentage of Mesozoic zircons abruptly decreased to nearly 0. The whole‐rock 87Sr/86Sr and εNd(t = 0) values changed significantly to 0.750124 and −15.8 for the Dumri Formation. The εHf(t) values of Early Cretaceous zircons in the Taltung Formation and Amile Formation plot in the U‐Pb‐εHf(t) field of Indian derivation, whereas εHf(t) values of Triassic‐Palaeocene zircons in the Bhainskati Formation demonstrate the arrival of Asian‐derived detritus in the Himalayan foreland basin in the Eocene based on available datasets. Our data indicate that (1) the timing of terminal India‐Asia collision was no later than the early‐middle Eocene in the central Himalaya, and (2) the Greater Himalaya served as a source for the Himalayan foreland basin by the early Miocene. When coupled with previous Palaeocene‐early Eocene provenance records of the Tethyan Himalaya, our new data challenge dual‐stage India‐Asia collision models, such as the Greater India Basin hypothesis and its variants and the arc–continent collision model. [ABSTRACT FROM AUTHOR]

Continental orogens that involve subduction and collision are important target areas for studying the growth, stabilization and transformation of Earth's continents. In particular, the nature of the lithospheric mantle and its relationship to the overlying crust in these active subduction-collision zones are key factors to be constrained. Mantle xenoliths entrained by Cenozoic basalts from the Indochina Block, the Sukhothai Arc and the Inthanon Zone (IB-SA-IZ) provide direct deep-seated samples of the lithospheric mantle derived from part of the Tethyan orogenic belt, offering a unique opportunity to study mantle processes during orogenesis in response to the closure of the Paleo-Tethys Ocean. The studied mantle xenoliths comprise 32 spinel lherzolites, six harzburgites, and one olivine websterite. We present a comprehensive study of the elemental geochemistry and Os isotopes of this sample suite. Their lithophile element systematics indicate that they represent mantle residues after varying degrees of melt extraction (5–24%), followed by melt refertilization. Although the highly siderophile element abundances have been affected to some extent by melt refertilization through removal of sulfides, the Os isotopic compositions of the studied xenoliths were minimally disturbed. Lherzolites and the sole olivine websterite from the IB-SA-IZ share similar Re-Os isotope systematics (187Os/188Os: 0.121–0.137) to global abyssal peridotites, representing juvenile lithospheric mantle accreted from the upwelling asthenosphere, most likely associated with arc-continent collision in response to the closure of the Paleo-Tethys Ocean and back-arc basin during the Middle-Late Triassic. In contrast, the refractory harzburgites from the Indochina Block and Sukhothai Arc are characterized by substantially lower 187Os/188Os ratios (187Os/188Os: 0.117–0.122) than the lherzolites, yielding Mesoproterozoic Re-depletion Os model ages, which can be interpreted as either ancient lithosphere relics beneath these regions or accreted ancient mantle debris from the upwelling asthenosphere. Although the interpretation for the origin of the older harzburgites is ambiguous, we can conclude that rejuvenation of the lithospheric mantle commonly occurred beneath different tectonic units of the Tethyan orogenic belt: i.e., the pre-existing lithospheric mantle beneath different tectonic units of the Tethyan orogenic belt has been largely replaced by upwelling asthenospheric mantle during the Middle-Late Triassic orogenesis. This mantle was then further refertilized to varying degrees by asthenosphere-derived melts. Both processes play key roles in defining the nature of the lithospheric mantle in orogenic settings. This study also highlights that the geodynamic processes in the lithospheric mantle beneath orogenic belts can be well constrained by integrated evidence from lithophile and highly siderophile elements and their isotopes (e.g., Os isotopes) of mantle xenoliths. [ABSTRACT FROM AUTHOR]

Quantitative isotopic paleoaltimetry has been applied in regions where Rayleigh distillation controls isotopic lapse rates. Air mass mixing and moisture recycling are viewed as complicating factors. We show here that, because of such effects, a cross‐Andean transect of meteoric water δD values precisely marks the geographic position of the Western Cordillera crest. This modern water signal is also recorded in Pliocene‐Pleistocene hydrated volcanic glass δD values. δD values between the Pacific coast and Western Cordillera exhibit no trend up to 2.5 km elevation and 100 km inboard, consistent with an arid climate in which Amazonian moisture is topographically blocked and Pacific moisture is efficiently recycled. The result is a large δD lapse rate (−98‰/km) and an abrupt horizontal δD shift (2‰/km) at the Western Cordillera crest. Therefore, we conclude that cross‐orogen δD transects could locate the ancient Western Cordillera crest. Plain Language Summary: Mountains have an outsized control on climate. Moist air masses rise and cool to cross high elevations, resulting in enhanced precipitation on the windward side and dry conditions downwind These processes influence the isotopic compositions of rainfall and of materials preserved in the geologic record that form from the interaction of rain with near‐surface materials. Here we report data from transects across the Peruvian Central Andes and show that the isotopic compositions shift abruptly at the position of highest topography (the crest of the Western Cordillera). This suggest that isotopic compositions of materials preserved in the geologic record might help establish the geographic position of the crests of mountain belts in the past. Key Points: There is a substantial shift in the hydrogen isotope ratios of meteoric water at the Andean Western Cordillera crestVolcanic glass younger than 5 million years old shows similar ratio distributions to modern soil and precipitation water valuesVolcanic arc migration over time can be identified with meteoric water stable isotope records [ABSTRACT FROM AUTHOR]

Palustrine‐lacustrine carbonates of the well‐dated Xichagou section (ca. 43 to ca. 13 Ma) next to the active Altyn Tagh Fault (ATF) are investigated in terms of abundance, lithofacies, strontium, carbon and oxygen isotopes, to differentiate tectonic and climatic controls on the evolution of intermontane lakes in the Tibetan Plateau. Volumetrically dominant siliciclastic strata document five depositional stages: mid‐Eocene alluvial fan (onshore), late Eocene fan delta (nearshore), Oligocene semi‐deep lake (offshore), early Miocene braided fluvial delta (nearshore) and mid‐Miocene fluvial plain (onshore). Carbonates are most abundant in the middle three lacustrine stages and contain various lithofacies, including calcretes, microbialites, grainstones and marlstones. Oxygen isotopes show two positive excursions (−1.17‰ and −2.59‰) at the first nearshore and late offshore stages, indicating two relatively saline stages linked to the Eocene and late Oligocene global warming climates. Carbon isotopes show a positive excursion (from −4.0‰ to +2.9‰) at the middle semi‐deep lake stage and meanwhile strontium isotopes of carbonates show a large negative excursion (from 0.7120‰ to 0.7113‰), both in response to the early Oligocene global humid and cooling climate and resultant lake expansion at the Qaidam Basin. Except for this lake expansion event, the first‐order lake transgressing, shallowing and regressing evolution at the Xichagou section were not consistent with Cenozoic global climatic change trends. Instead, the two‐stage strike‐slip faulting of the ATF probably induced the northeastward and eastward migration of basin depocenter and resulted in the lake transgression‐regression at the Xichagou section. The widespread presence and relatively minor variation in oxygen isotopes (from −7.5‰ to −7.0‰) of early Miocene microbialites in the northern Tibetan Plateau suggest a warm climate and a low relief before ca. 15 Ma. [ABSTRACT FROM AUTHOR]

The publication presents the results of geochemical, isotopic-geochemical (Sm–Nd) and isotopic-geochronological (U–Th–Pb) studies of terrigenous rocks of the Middle Riphean (?) Nadarov Formation and the Upper Riphean (?) Nortui Formation of the northwestern part of the Argun continental massif. The composition of the deposits indicates the presence of formations of various silica content in the source area. According to Sm–Nd data, sedimentary rocks of the Nadarov and Nortui formations are characterized by negative values of εNd(t) = –6.6...–3.5 at Early Proterozoic values of Nd model age (tNd(DM) = 2.0–1.8 Ga). The U–Th–Pb dating of detrital zircon grains showed that the lower age limit of accumulation of terrigenous deposits of the Nadarov and Nortui formations falls to the Late Riphean (~775 and ~ 744 Ma, respectively). The main provenance areas for them were Late Riphean igneous rocks, with participation of Early Proterozoic rocks occurring in the Argun Massif. [ABSTRACT FROM AUTHOR]

The Wulonggou Gold Field is one of the giant gold fields in the East Kunlun Orogenic Belt, northwestern China. Previous studies mainly focused on elementary mineral isotopic studies, fluid inclusions, and geological features in the Wulonggou Gold Field. In this study, we report some research on the precise age and the specific ore-forming process of the WGF: the hydrothermal monazite U–Pb ages; the way of gold precipitation; the composition, evolution, and source of ore-forming fluids of the Wulonggou Gold Field. Finally, we demonstrate a link between two-stage hydrothermal events and sequential episodes of crust-derived magmas, with implications for gold metallogeny in the East Kunlun Orogenic Belt. There are four hydrothermal stages that are recognized: a quartz–pyrite stage (stage 1), a quartz–pyrite–arsenopyrite–chalcopyrite stage (stage 2), a quartz–galena–sphalerite–pyrite stage (stage 3) and a quartz–stibnite–carbonate stage (stage 4). The monazite U–Pb ages of the Huanglonggou and Hongqigou deposits in the Wulonggou Gold Field were 422.2 ± 2.4 Ma and 236.7 ± 3.7 Ma, respectively, which support the opinion of two epochs of mineralization. Stages 1 and 2 are the main gold mineralization stages, wherein Au and As have a close genetic relationship. The Hongqigou and Huanglonggou deposits seem to have been formed in different metallogenic events due to the contrast on the trace element compositions in pyrite. The sources of the ore-forming materials and fluids of the Hongqigou and Huanglonggou deposits show apparent characteristics of orogenic gold deposit, and the magmatic events during Paleozoic and Mesozoic have an important contribution to the formation of the gold deposits. The gold deposits in the Wulonggou Gold Field can be interpreted as an orogenic gold system related to two-epoch tectonic–magmatic events. [ABSTRACT FROM AUTHOR]

[Display omitted] • The migmatite records the evolution of the Dabie orogen from Triassic to Cretaceous. • The upwelling asthenosphere provided a heat source for the Triassic metamorphism. • The migmatite is the product of multiple anatexis of the subducted continental crust. The Dabie orogen underwent a 'complete' orogenic cycle from Triassic collisional orogeny to Early Cretaceous tectonic collapse. Zircons of the migmatite in the North Dabie terrane recorded the processes from Triassic granulite-facies metamorphism to Early Cretaceous anatexis. Three types of zircon are recognized in the migmatite: the Neoproterozoic inherited magmatic zircon, the Triassic metamorphic zircon, and the Late Jurassic–Early Cretaceous anatectic zircon. The Neoproterozoic inherited magmatic zircons suggest the protolith of the migmatite has a tectonic affinity with the Yangtze Craton (YC). The Triassic metamorphic zircon domains have variable ε Hf (t) values from −4.1 to 3.6 and low δ18O compositions ranging from −4.36‰ to −0.30‰. The anatectic zircon domains have clearly negative ε Hf (t) values of −19.8 to 0.8 (mostly less than −10.0) and relatively high δ18O values from −4.24‰ to 3.49‰. Based on the chronological and isotopic data of migmatite and the results of previous studies, the Triassic granulite-facies metamorphism was closely related to the asthenosphere upwelling after the slab break-off during the orogenic stage, and the Early Cretaceous anatexis respond to widely heat event during the collapse stage of orogen. [ABSTRACT FROM AUTHOR]

The crystallization age of the Sunjiafen Formation volcanic rocks is 253.9 ± 1.1 Ma. Geochemical data show that these volcanic rocks belong to the shoshonitic and metaluminous series and have high Sr and low Y contents (461–582 and 5.60–6.74 ppm, respectively), MgO = 1.32–2.65 wt%, and Na2O/K2O = 0.81–1.40. In MgO−SiO2, Cr−SiO2, Sr/Y−Y and (La/Yb)N−YbN diagrams, data for the samples plot in the adakite and "adakite related to thickened lower crust" fields. As such, we suggest that the Sunjiafen Formation C−type adakitic andesites formed in a compressional tectonic setting. The youngest age (youngest peak age) of two sandstone samples from the Linxi Formation are 251 Ma (257 Ma) and 237 Ma (254 Ma). Detrital zircons with ages of >1500 Ma have εHf(t) values of −5.87 to +6.31. A comparison of the age spectra and εHf(t) values of the detrital zircons in the Linxi Formation with those of igneous zircons from the Central Asian Orogenic Belt and North China Craton indicates the formation was derived from both the belt and the craton. We identified "Jura–type Folds" that formed in peripheral foreland basin in the Linxi Formation, and along with plant fossil fragments (Paracalamites frigidus). These and previously published results indicate the Paleo–Asian Ocean closed along the Xar Moron–Changchun Suture zone during the Late Permian. The study area was in a continuous compressional setting during the Late Permian and formed a peripheral foreland basin that was related to continent–continent collision. [ABSTRACT FROM AUTHOR]

Zircon is an important accessory mineral for studying the crust-mantle interaction and crustal growth through time because zircon crystals not only allow precise dating but also record initial Hf isotope ratios of the host magma. Our study on a suite of gabbronorite, mafic diorite cumulate, diorite and granite from the Kekeli Batholith in the North Qilian Orogenic Belt, Northern Tibetan Plateau, shows (1) a significant Hf isotope discrepancy between zircon and their bulk rocks; and (2) bulk-rock Nd-Hf isotope decoupling. These observations thus demonstrate that zircons do not always capture the full history of magmatic system. The significant positive correlation between bulk-rock Hf isotope ratios and TiO 2 content (R 2 = 0.94) indicates that Ti-rich minerals (e.g., ilmenite, amphibole) are likely important Hf hosts. The early-formed Ti-rich minerals possibly record different Hf isotopes from those of zircons crystallized subsequently, thus causing discrepancy between zircon and bulk-rocks and leading to bulk-rock Nd-Hf isotope decoupling. Correlations between bulk-rock TiO 2 content, Mg isotopes and Hf isotopes indicate a mixing process, with granite and gabbronorite representing two compositional endmembers. Because Ti minerals have higher crystallization temperatures than zircons, when the mixing melts have contrasting isotopes (or from heterogeneous sources/have a strong crustal contamination), the bulk-rock and zircon Hf isotope discrepancies reflect mineral crystallization sequence during mafic and felsic magma mixing. It is thus imperative to consider early formed minerals such as Ti-rich minerals and the bulk rock composition, not just zircons, when using Hf isotopes to track melt evolution and precisely constrain mantle contribution to granitoid petrogenesis. [ABSTRACT FROM AUTHOR]